As a piece of general advice, Googling “Du Revest” “Saunders” and “1757” (with the names in quotation marks) would probably get you a hit on an account of the action, and choosing "Books" as the type of location would get you published accounts. Was Saunders out of Gibraltar, trying to intercept du Revest running through the Straits?

I happen to have O. Troude, Batailles navales de la France (4 vols.; Paris: Challamel Ainé, 1867), a good source for this kind of information, already printed out and on my shelf, but Léon Guérin, Histoire maritime de la France (6 vols.; Paris: Dufour et Mulat, 1851) would probably have it too. Troude doesn’t mention the encounter with Saunders but says (vol. I, p. 341) that du Revest showed up at Louisbourg on June 15, 1757, withHector, 74, Capt. Durevest (Troude spells the name as all one word)Achille, 64, Capt. PannatVaillant, 64, Capt. Sauvins Murat (I think this should be Saurins)Sage, 64, Capt. d’AbonComète, 32, CO not given

Actually, on the next page Troude does have an account of an encounter on April 5 in the Strait of Gibraltar between du Revest and Saunders with Culloden, Berwick, Princess Louisa, Portland, and Guernsey. My experience with the preceding war is that everybody got what the other guys were doing or who they were wrong to some extent, by omission or commission, so writers like Beatson and Clowes should not be relied on solely to understand what happened. If one of them is the source of the Three Decks account, it is almost certainly in error in some respect, and probably not just in omitting the names of the French ships. And I wouldn't trust Troude to have the story 100% correct either (or even Guerin).☺

The original source for the British vessels is the Seven Years War project at http://www.kronoskaf.com/syw/index.php?title=Main_Page which is as reliable as many and reasonably well researched. It list four of the French vessels as part of de Revest's squadron at Louisbourg

No longer any sign of Saunders vs. du Revest at kronoskaf: nothing under "Battles" for 1757, nothing on the "navies" page, no reference to du Revest on the officers or commanders page. If you want more details of the action, and Google the three search terms "Saunders" "Revest" and "1757" you can find a description in a German work, Pragmatische Staatsgeschichte des letztern Krieges bis auf den Hubertsburg Frieden, Volume 1 (1767, in German, and printed in Fraktur), §377 on page 509.

Yes, well, there is a lot of that going around these days.☺ I don't want to research this further myself, but if you want more details from the French side (the obvious British source is the captains' journals and any report by Saunders in the admirals' in-letters), here are some suggestions:

La Courrier d'Avignon—Published outside French censorship in Papal territory, but dependent on the French postal system for distribution. At https://gallica.bnf.fr/ark:/12148/cb32780022t/date you can select the year 1757 and then start trolling through issues beginning around April 12 or 15 (two per week).

Gazette (Paris)—Known as the Gazette de France although "de France" doesn't appear on the masthead. The official line, one of three officially sanctioned newspapers in France (weekly). The Gallica site has whatever the Bibliothèque National de France had in their collections. There were regional collections and there is a good run of the Lyon edition on line; I use it for years for which I can't find a complete run of the Paris edition.

Dutch newspapers published in French (nobody outside the Netherlands could read Dutch) might also have reports. The "Gazette de Leyde" (Leide), formally titled Nouvelles extraordinaires de divers endroits, semi-weekly, was in the process of earning a reputation for reliability. Some bound annual runs have made it into Google Books or other digitization projects. The Europeana site has digitized a lot from the Bayerische Staatsbibliothek (Bavarian State Library). Google both the title and the year to find a 1757 run.

Usually quite a long time afterwards, the British general-interest monthlies, London Magazine, Gentleman's Magazine, and Scots Magazine published letters containing personal observations of naval battles; in the 1740s this was done only for major battles, so there might not be anything except an uninformative brief notice. There's also the possibility of a London Gazette notice from a dispatch by Saunders, but that's probably what Beatson (probably Clowes' source) used, so it might not have anything more than what you already know.

Sorry, https://gallica.bnf.fr/ark:/12148/cb32780022t/date is for the Paris Gazette, and they do have all 53 issues from 1757. Le Courrier (Avignon) is at http://www.gazettes18e.fr/courrier-avignon; click on "Consulter la gazette." The Leiden gazette is at http://www.gazettes18e.fr/gazette-leyde. You have to select a year, then an individual issue, and then select the pages individually, which is less convenient than a PDF of a bound volume of 53 or 105 issues that you can scroll through.